The level of parity in the NFL surely has to be at an all-time high. It's getting harder and harder to predict weekly matchups.

After back-to-back thrashings of both the Jets and the Bills, it would have been silly to think that San Francisco would get blown out at home. The 49ers are incredibly tough at home, and coming into Week 6, a Jim Harbaugh-led team was 10-1 at Candlestick Park. Its only regular-season loss came in his second game as a head coach.

When the 49ers lost to the Vikings on the road, I actually wasn't that surprised. Sure, I picked them to win that game, but winning on the road in the NFL is extremely tough. The Giants are a tough team in their own right, yet going into yesterday's contest, the NFC West was an impressive 10-0 at home.

So what led to the 49ers laying an egg in their 26-3 loss? Surely, most will lay the blame on offensive coordinator Greg Roman and quarterback Alex Smith. But I'm here to shift your focus to a defense that has regressed in terms of productivity.

Yardage-wise, the 49ers are currently touted as the No. 1 defense in the NFL. Yet yesterday's loss allows you to key in on their biggest problem right now. Going forward, San Fran needs to do a better job at getting after the quarterback and taking advantage of individual matchups.

By analyzing the numbers and breaking down the tape, let's take a look at why the defensive pass rush has taken a step back.

Aldon Smith

Even with a couple of blowout wins under their belt, the 49ers' ability to rush the passer just isn't as dominate as it was last season. Pro Football Focus had Fangio's defense as the second most effective pass-rushing unit in the NFL at last season's end.

Where is it right now? An embarrassing 12th from the bottom. In last night's article, I begged the question: Are increased snaps causing Aldon Smith to be less productive this year? If you look at the number of snaps he has played and his productivity on those snaps, you would have to say yes.

By season's end in 2011, Smith was averaging a quarterback pressure once every five pass rush opportunities. He finished the season with 14 quarterback sacks, 17 quarterback hits and 43 hurries. There was no 3-4 outside linebacker that averaged a pressure as often as he did.

So you may be wondering, what is his pass rushing efficiency now? He has a total of 20 pressures right now. His current rate is one pressure every eight pass rushing opportunities. A three-snap difference may not seem like much. But if you add it up over the entire year, it will take him almost twice as long to reach the same accolades.

Aside from the increased snaps, here is another reason as to why Smith's productivity has gone down. He isn't seeing as many one-on-one matchups as he saw last year. The Giants did a great job of helping out on him yesterday.

Left tackle William Beatty had help more than once off the edge. New York would either give tight end help to Beatty or chip with a running back while he was on his way out. In the illustration above, you can see that Bradshaw acts like he is going out on a route, but instead he stays in to help out on Smith.

Two-against-one matchups are beatable, yet the rate a player will beat them is very low. In theory, if a team doubles one pass rusher, another should be getting pressure against an individual opportunity, whether that is on the opposite side or right up the middle.

However, if a player is not able to win those one-on-one battles, then the opposing team can continue to utilize the double-team. That's essentially what is currently happening to the 49ers. Justin Smith, Isaac Sopoaga and Ray McDonald aren't winning their individual matchups at the same rate they were in 2011.

Justin Smith

In terms of what's wrong with A. Smith, we have a general idea that I expressed above. Fortunately, I think his problems generally relate to J. Smith's as well.

At the end of last season, PFF had Smith as the most effective pass-rushing 3-4 defensive end in the site's history. His grade was a plus-30.2. The next closest player in that same category was five points behind him.

Through six games in 2011, his pass rush grade was plus-14.9. If you're not familiar with PFF's grading, they grade players very conservatively. Through six games this year, Smith's negative-2.9 grade is the worst of the entire defense. Hard to believe he has fallen off that much in one year.

If we run the numbers just like we did with A. Smith, you realize that he's only averaging a quarterback pressure once every 23 snaps. When I compared that to last year's rate of one pressure every eight snaps, I was blown away.

By turning on the tape, you begin to see a lot of the same things that teams are doing to A. Smith. The double-teams, chip blocks and holds the offensive line gets away with are incredible. Yet if this is truly the case, why aren't other defenders getting pressure? It's simple.

Like the Giants, teams are holding extra blockers in to protect the quarterback, which in turn forces the cornerbacks to cover for longer periods of time on the back end. No matter how good a cornerback is, he can't cover forever. A good wide receiver will eventually win that battle.

Even though the Giants weren't overly effective throwing the ball yesterday, they made sure to protect Eli Manning. The 49ers only laid a hand on him once—they finished the day with zero sacks and one quarterback hit.

New York used a fullback and a tight end on over 50 percent of their offensive plays. The philosophy of holding in extra blockers won't work for every team because not every club has Victor Cruz, Hakeem Nicks and Martellus Bennett as pass-catchers.

With that being said, I don't think it's time to panic yet. The season is very long, and after a productive season in 2011, it should have been expected that Fangio's two best pass-rushers would garner more attention in 2012.